The present invention relates to a pulsimeter, a frequency analysis device, and a pulse measurement method. For example, the present invention relates to a pulsimeter, a frequency analysis device, and a pulse measurement method which perform a frequency analysis.
A pulsimeter configured using a pulse sensor including a light emitting device, such as an LED (light emitting diode), and a photodetector, such as a phototransistor or a photodiode, is known. As a method of obtaining a pulse rate from an output of the pulse sensor, there is a method in which a frequency analysis is performed by performing Fourier transform processing on the output from the sensor and a pulse rate is calculated based on the analysis result.
Due to the nature of the Fourier transform processing that calculates frequency components of input data, the Fourier transform processing requires an approximate number of pieces of input data, i.e., an approximate number of samples. The number of pieces of input data depends on a measurement time. In order to calculate a pulse rate with a high resolution and extend the upper limit of a measurement range, it is necessary to increase the number of pieces of input data. Accordingly, when the Fourier transform processing is performed on a predetermined sample number of data sequences so as to satisfy the performance required by a system, the Fourier transform processing cannot be performed until a necessary number of pieces of input data are obtained, so that it takes a long time to output the pulse rate.
On the other hand, Japanese Unexamined Patent Application Publication No. H10-258039 discloses a technique in which in fast Fourier transform (FFT) processing using 128 pieces of sampling data as a processing unit, the FFT processing is performed on 128 pieces of latest pulse wave data every time 32 pieces of pulse wave data are acquired, thereby shortening the time required for outputting the result.